Utility companies use power meters to regulate and monitor power usage. Early power meters were electromechanical in nature converting the flow of electricity through the power meter into mechanical movement. The mechanical movement was used to turn a recording device which recorded the amount of energy being used. As technology improved over the years, the design of the power meter incorporated new innovations such as increased processing capability within the meter, elimination of mechanical parts, better accuracy and the like.
The power meter typically monitors and measures the amount of power that the utility consumer uses. Additionally, the utility meter may monitor the real time conditions that exist at the utility customer's site. Within the power meter, internal circuitry such as processors, microprocessors, microcontrollers or the like may perform these monitoring functions. In order to operate, the internal circuitry may require a DC (direct current) power supply.
Within the power meter, the DC power supply may connect directly to the utility lines that couple the utility meter to the power grid. Under normal operating conditions, the power meter may experience voltage ranging from about 70 VAC to about 288 VAC. The DC power supply converts the AC voltages to a constant DC voltage. The converted DC voltage typically ranges between 3 VDC to about 12 VDC. In addition to converting the AC voltages to a DC voltage, the power meter must be able to withstand surges in the AC voltage. Occasionally, the utility lines may experience large surges in voltage due to lightning strikes or other over voltage conditions. In order to provide a constant DC voltage as well as over voltage protection, the DC power supply may contain a multitude of discrete components. In previous power meters, the discrete components of the DC power supply required significant space on the power meter's circuit board. Some discrete components contained within the power meter's internal circuitry may include a 60 Hz transformer, various inductors, capacitors, resistors and transformers or the like.
As technology has advanced, the characteristics of many of the discrete components began to evolve. In previous power meters, a dedicated discrete inductor is used as an energy storage unit to provide voltage into a switching voltage regulator. Thus when the AC voltage dropped below a particular voltage threshold, the discrete inductor discharged and continued to provide voltage to the switching regulator until the incoming AC waveform returned to the voltage threshold.